The country star appears on Sunday's upcoming episode of Sunday TODAY With Willie Geist and gives insight into the start of his relationship with the pop princess.

"When I was going through my divorce and just hit rock bottom, just like anyone does when they go through something that devastating, it's a miracle that I met somebody that was going through the same exact thing that I was at the exact same moment in time," Shelton, 42, says.

Both Shelton and Stefani, 48, divorced their partners — Miranda Lambert and Gavin Rossdale respectively — in 2015, before confirming their relationship in November of that year. For that reason, many people, Shelton and Stefani included, assumed they would have a quick rebound relationship.

"I think if Gwen and I were being honest right now talking about this, I think in the back of our minds we both kind of thought this is a rebound deal," Shelton reveals. "I mean, because we're both coming out of a pretty low spot in our lives and we're kind of clinging to each other to get through this."

LAS VEGAS, NV - APRIL 15: Blake Shelton (L) and Gwen Stefani attend the 53rd Academy of Country Music Awards at MGM Grand Garden Arena on April 15, 2018 in Las Vegas, Nevada. (Photo by Jeff Kravitz/ACMA2018/FilmMagic for ACM)

LAS VEGAS, NV - APRIL 15: Blake Shelton (L) and Gwen Stefani attend the 53rd Academy of Country Music Awards at MGM Grand Garden Arena on April 15, 2018 in Las Vegas, Nevada. (Photo by Jeff Kravitz/ACMA2018/FilmMagic for ACM)

LAS VEGAS, NV - APRIL 15: Blake Shelton and Gwen Stefani attend the 53rd Academy of Country Music Awards at MGM Grand Garden Arena on April 15, 2018 in Las Vegas, Nevada. (Photo by John Shearer/ACMA2018/Getty Images for ACM)

LAS VEGAS, NV - APRIL 15: Blake Shelton and Gwen Stefani attend the 53rd Academy of Country Music Awards at MGM Grand Garden Arena on April 15, 2018 in Las Vegas, Nevada. (Photo by Jason Merritt/ACMA2018/Getty Images for ACM)

LAS VEGAS, NV - APRIL 15: Blake Shelton and Gwen Stefani attend the 53rd Academy of Country Music Awards at MGM Grand Garden Arena on April 15, 2018 in Las Vegas, Nevada. (Photo by John Shearer/ACMA2018/Getty Images for ACM)

@blakeshelton have a good show tonight we r missing u in L.A.❤️ gx

#youmakeitfeellikechristmas @nbcthevoice @blakeshelton #backstage gx

#❤️ #countrymusicfreakstour2018 @blakeshelton #stlouismissouri gx

Yay!! It was incredible to write with @BlakeShelton & share the stage for a song that is so joyful & Christmas-y! #YouMakeItFeelLikeChristmas #LuckyGirl 💋✨

EAST HAMPTON, NY - AUGUST 20: Blake Shelton and Gwen Stefani attend the Apollo in the Hamptons 2016 party at The Creeks on August 20, 2016 in East Hampton, New York. (Photo by Patrick McMullan/Patrick McMullan via Getty Images)

EAST HAMPTON, NY - AUGUST 20: Blake Shelton and Gwen Stefani perform at Apollo in the Hamptons 2016 at The Creeks on August 20, 2016 in East Hampton, New York. (Photo by Kevin Mazur/Getty Images for The Apollo)

EAST HAMPTON, NY - AUGUST 20: Blake Shelton, Gwen Stefani and Ronald O. Perelman attend Apollo in the Hamptons 2016 at The Creeks on August 20, 2016 in East Hampton, New York. (Photo by Kevin Mazur/Getty Images for The Apollo)

EAST HAMPTON, NY - AUGUST 20: Blake Shelton and Gwen Stefani attend Apollo in the Hamptons 2016 at The Creeks on August 20, 2016 in East Hampton, New York. (Photo by Kevin Mazur/Getty Images for The Apollo)

LAS VEGAS, NEVADA - MAY 22: Blake Shelton and Gwen Stefani are seen on stage during the 2016 Billboard Music Awards held at the T-Mobile Arena on May 22, 2016 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)

GLENDALE, AZ - DECEMBER 27: Gwen Stefani and Blake Shelton wave to fans prior to the NFL game between the Green Bay Packers and Arizona Cardinals at University of Phoenix Stadium on December 27, 2015 in Glendale, Arizona. (Photo by Norm Hall/Getty Images)

GLENDALE, AZ - DECEMBER 27: Musicians Gwen Stefani and Blake Shelton attend the NFL game between the Green Bay Packers and Arizona Cardinals at the University of Phoenix Stadium on December 27, 2015 in Glendale, Arizona. (Photo by Christian Petersen/Getty Images)

GLENDALE, AZ - DECEMBER 27: Musicians Gwen Stefani and Blake Shelton attend the NFL game between the Green Bay Packers and Arizona Cardinals at the University of Phoenix Stadium on December 27, 2015 in Glendale, Arizona. (Photo by Christian Petersen/Getty Images)

Cast member Blake Shelton and singer Gwen Stefani laugh at the party following the premiere for "The Angry Birds Movie" in Los Angeles, U.S., May 7, 2016. REUTERS/Mario Anzuoni

"Now here we are, going on three years later, and every day that goes by it just feels like a stronger bond between the two of us and it constantly feels like it's going to the next level," Shelton says. "That's the only way I think either one of us could describe it if she was sitting right here."

The musicians have been especially sweet the last couple of weeks. Stefani celebrated Shelton's birthday over the weekend with dinner at BOA Steakhouse in West Hollywood, California, and a cookout on Father's Day. On Tuesday, Stefani shared snaps from her time with Shelton in his home state of Oklahoma. The couple, along with Stefani's sons — Kingston, 12, Zuma, 9, and Apollo, 4 — spent time on a boat and out in nature.

Despite their obvious love for each other, the duo is in no rush to tie the knot.

"There is no reason for them to rush into a marriage, so they aren’t," a source exclusively told ET back in March. "Both of them are happy and content with where their relationship is right now."

The source continued: "They are on cloud nine for each other. They are perfect for each other. They know they have found their true soulmate."

In April, however, the country superstar admitted to thinking about marrying his longtime love.

"I think about [marrying her]. I don't think it's anytime soon or anything," he said during an interview with CMT. "The more time that goes by, I guess, the closer you'd be getting to that."

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Miranda Lambert and Blake Shelton together

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Miranda Lambert and Blake Shelton together

INDIO, CA - APRIL 28: Musicians Blake Shelton and Miranda Lambert perform onstage during the Stagecoach Country Music Festival held at the Empire Polo Field on April 28, 2012 in Indio, California. (Photo by Christopher Polk/Getty Images for Stagecoach)

LAS VEGAS, NV - APRIL 06: Recording artist Miranda Lambert (R) accepts the Single Record of the Year award for 'Mama's Broken Heart' onstage from co-host Blake Shelton during the 49th Annual Academy of Country Music Awards at the MGM Grand Garden Arena on April 6, 2014 in Las Vegas, Nevada. (Photo by Ethan Miller/Getty Images)

LAS VEGAS, NV - APRIL 07: Musician Blake Shelton and singer Miranda Lambert attend the 48th Annual Academy of Country Music Awards at the MGM Grand Garden Arena on April 7, 2013 in Las Vegas, Nevada. (Photo by Frazer Harrison/ACMA2013/Getty Images for ACM)

NASHVILLE, TN - JUNE 04: Miranda Lambert and Blake Shelton attend the 2014 CMT Music awards at the Bridgestone Arena on June 4, 2014 in Nashville, Tennessee. (Photo by Mike Coppola/WireImage)

NASHVILLE, TN - JUNE 13: Singer/Songwriter Blake Shelton is joined by Singer/Sonwriter and Fiancee Miranda Lambert during the 2010 CMA Music Festival on June 13, 2010 in Nashville, Tennessee. (Photo by Rick Diamond/Getty Images)

NASHVILLE, TN - MARCH 15: Grand Ole Opry Member Blake Shelton and Miranda Lambert performs during the 40th Anniversary of The Grand Ole Opry House on March 15, 2014 in Nashville, Tennessee. (Photo by Rick Diamond/Getty Images)

NASHVILLE, TN - JUNE 13: Singer/Songwriter Blake Shelton is joined by Singer/Sonwriter and Fiancee Miranda Lambert during the 2010 CMA Music Festival on June 13, 2010 in Nashville, Tennessee. (Photo by Rick Diamond/Getty Images)

NASHVILLE, TN - JUNE 13: Singer/Songwriter Blake Shelton is joined by Singer/Sonwriter and Fiancee Miranda Lambert during the 2010 CMA Music Festival on June 13, 2010 in Nashville, Tennessee. (Photo by Rick Diamond/Getty Images)